Walk-in bathtubs comprise high tub walls with a high built in seat and a side door, allowing the user to walk into the tub from the side and sit down without having to climb down into a low bath tub. FIG. 1 shows a typical example of a walk-in bathtub in accordance with the prior art. Walk-in tubs are particularly suited for individuals who have physical limitations that make it difficult or dangerous to climb into and out of a regular, low bathtub or to stand up in a shower for extended periods of time. Such limitations might include physical disabilities or simply the reduced strength, balance and range of motion that typically occur with advancing age. Walk-in tubs are not only easier to enter and exit than conventional bathtubs, they also reduce the chances of slips and falls compared to conventional tubs and showers.
In addition to safety, the ease of entering the tub via the side walk-in door also provides users with independence, allowing them to bathe without the assistance of another person when getting into and out of the tub.
Typically, the side doors used with walk-in tubs have two-part hinges that are screwed directly into the tub wall. This mounting configuration is analogous mounting a house door directly onto the wall instead of a frame. This design lacks the benefit of the additional structural integrity provided by a door frame, which can help keep the walls of the tub from flexing.
Because of their depth, walk-in bathtubs are typically made from gel-coated fiberglass, including the side doors. However, acrylic is the preferred material for conventional bathtub manufacturers because it is germ and stain resistant, has good heat retaining qualities, keeps its luster longer and is durable. Because acrylic is non-porous, it resists mold and mildew making it easier to clear. The reason for using fiberglass in manufacturing walk-in tubs lies in the technical difficulties in forming the deep basin of the tub with a single sheet of acrylic. Do to the depth of the tubs and seat heights approaching 17 inches above the tub floor, acrylic has a tendency to tear during the vacuum forming process or become excessively thin at the bottom, comprising its ability to hold the requisite water weight.
New manufacturing methods are now making it possible to vacuum form deep walk-in tubs using acrylic sheets. However, vacuum forming acrylic typically results in surface inconsistencies that are very difficult if not impossible to eliminate. Because the conventional door design for walk-in tubs relies upon direct contact between the door and tub wall to maintain the water seal, this design is ill suited for use with acrylic tubs due to the surface inconsistencies, especially if the door is also made of acrylic. Additionally, unlike gel-coated fiberglass walk-in bathtubs, with acrylic it is very difficult if not impossible to create a finished door threshold during the forming process, resulting in labor intensive production steps to create the finished surface.
Therefore, there is a need for an improved door design for walk-in bathtubs that includes the benefits of a pre-hung door assembly and is capable of maintaining the proper water seal and speed up the production process when implemented with acrylic tubs.